Genetic and environmental contributions to the development of soft tissue facial profile: a twin study.

OBJECTIVES: This study aimed to determine the relative contribution of genetic and environmental factors in the phenotypic variation of the soft tissue facial profile during the mixed dentition and the permanent dentition stages. METHODS: In this retrospective cohort study, standardized facial profile photographs of 139 twin pairs (55 monozygotic and 84 dizygotic) were obtained from archival records at the Adelaide Dental School. Photographic analysis used 12 angular and 14 linear facial profile measurements from the mixed dentition (7-11 years) to the permanent dentition (12-17 years) stages. A genetic analysis was performed using a univariate structural equation model adhering to the normal assumptions of a twin model. RESULTS: In the mixed dentition stage, the additive genetic (A) and unique environment (E) model, AE model, was the most parsimonious in explaining the observed phenotypic variance for all 26 facial traits with the narrow-sense heritability estimates ranging between 0.38 and 0.79. In the permanent dentition, the AE model was the most parsimonious for 20 out of 26 traits, however, the variance of six traits, particularly those in the lower third of the face, was best explained by the shared environmental and unique environmental factors. LIMITATIONS: This study exclusively included twins of European ancestry. CONCLUSIONS: The soft tissue facial profile demonstrated dynamic genetic and environmental influences with a greater additive genetic influence during the mixed dentition and the early stages of the permanent dentition. However, there was evidence of increasing environmental influence in the lower third of the face during the early stages of the permanent dentition.

Heritability of dental arches and occlusal characteristics: a systematic review and meta-analysis.

BACKGROUND AND OBJECTIVE: The genetic basis of dentoalveolar characteristics has been investigated by several studies, however, the findings are equivocal. The objective of this systematic review and meta-analysis was to evaluate the heritability of dental arches and occlusal parameters in different stages of human dentition. SEARCH METHODS: Electronic databases PubMed, Embase, Scopus, Web of Science, and Dentistry and Oral Science Source were searched up to August 2023 without the restriction of language or publication date. SELECTION CRITERIA: Empirical studies investigating the heritability of dentoalveolar parameters among twins and siblings were included in the review. DATA COLLECTION AND ANALYSIS: Study selection, data extraction, and risk of bias assessment were performed independently and in duplicate by two authors and a third author resolved conflicts if needed. Joanna Briggs Institute's critical appraisal tool was used to evaluate the risk of bias among studies and the certainty of evidence was assessed using the Grading of Recommendation, Assessment, Development, and Evaluation (GRADE) criteria. RESULTS: Twenty-eight studies were included in the systematic review, of which 15 studies reporting heritability coefficients in the permanent dentition stages were deemed suitable for the meta-analysis. Random-effects meta-analyses showed high heritability estimates for maxillary intermolar width (0.52), maxillary intercanine width (0.54), mandibular intermolar width (0.55), mandibular intercanine width (0.55), maxillary arch length (0.76), mandibular arch length (0.57), and palatal depth (0.56). The heritability estimates for the occlusal parameters varied considerably, with relatively moderate values for crossbite (0.46) and overbite (0.44) and low values for buccal segment relationship (0.32), overjet (0.22), and rotation and displacement of teeth (0.16). However, the certainty of evidence for most of the outcomes was low according to the GRADE criteria. CONCLUSIONS: Based on the available evidence, it can be concluded that the dental arch dimensions have a high heritability while the occlusal parameters demonstrate a moderate to low heritability. REGISTRATION: PROSPERO (CRD42022358442).

New regression equations for mixed dentition space analysis in Nepalese mongoloids.

BACKGROUND: Mixed dentition space analysis methods using regression equations, namely, Moyers' analysis and Tanaka-Johnston analysis are commonly used around the world. However, the applicability of these analyses among different racial groups have been questioned. The primary objective of this study was to assess the applicability of the Moyers' and Tanaka-Johnston analyses among Nepalese Mongoloids and to develop regression equations for the same population if needed. METHODS: One hundred (50 males and 50 females) pre-treatment study models of the Nepalese Mongoloid patients undergoing orthodontic treatment were retrieved from the archives of the department of Orthodontics. The mesiodistal widths of mandibular incisors and widths of canines and premolars of all 4 quadrants were measured by a single investigator using a digital caliper to the nearest 0.01 mm. Predicted widths of canines and premolars were obtained using standard Moyers' and Tanaka-Johnston analyses and then compared with the measured widths. RESULTS: The measured widths of canines and premolars were significantly different from the predicted widths obtained from Moyers' and Tanaka-Johnston analyses. Strong and positive correlations were found between the sum of mesiodistal widths of mandibular incisors and the sum of mesiodistal widths of canines and premolars in males (0.73 for maxillary arch and 0.68 for mandibular arch) and females (0.64 for maxillary arch and 0.79 for mandibular arch). CONCLUSIONS: The Moyers' and Tanaka-Johnston analyses did not accurately predict the mesiodistal width of unerupted canines and premolars for Nepalese Mongoloid population. Hence, new regression equations have been developed for this population. However, validation studies should be conducted to confirm the applicability and accuracy of these equations.

The morphology and bridging of the sella turcica in adult orthodontic patients.

BACKGROUND: The purpose of this study was to determine and compare the shapes, sizes, and bridging of the sella turcica in patients with different skeletal patterns and genders. METHODS: It was a cross-sectional comparative study. The samples were divided into three groups according to the skeletal pattern viz. Class I, Class II and Class III, and each group consisted of 40 samples (20 males and 20 females). The lateral cephalograms were traced and the sella turcica was assessed for its size, shape, and bridging. RESULTS: The mean length, anteroposterior diameter and depth of sella turcica were 8.13 ± 2.03 mm, 9.60 ± 1.43 mm and 6.40 ± 1.21 mm respectively. The mean length of sella turcica was 7.91 ± 1.52 mm in Class I, 7.32 ± 1.62 mm in Class II and 9.16 ± .2.42 in Class III skeletal pattern; anteroposterior diameter was 9.30 ± 1.02 mm in Class I, 9.15 ± 1.28 mm in Class II and 10.35 ± 1.64 mm in Class III skeletal pattern; and the depth was 6.40 ± 0.92 mm in Class I, 6.07 ± 1.01 mm in Class II and 6.74 ± .1.54 mm in Class III skeletal pattern. There were significant differences in length and anteroposterior diameter and sella turcica between Class I, Class II and Class III skeletal patterns (p = 0.01), (p = 0.01) respectively. There was no significant difference in size of sella turcica between different genders and age groups. Sixty percent of the patients studied had normal Sella morphology. Partial Sella turcica bridging and Sella turcica bridging was seen in this study in 23.33% and 11.67% of patients respectively. CONCLUSION: Sixty percent of the patients had normal sella turcica. There were significant differences in lengths and anteroposterior diameters among Class I, Class II and Class III patients. The larger size was present in skeletal Class III patients.

Comparative evaluation of arch form among the Nepalese population: A morphological study.

Aims: The study aims to identify sexual dimorphic features in the arch patterns based on tooth arrangement patterns and the maxillary and mandibular arches using Euclidean Distance Matrix Analysis (EDMA). Settings and Design: A total of 96 Nepalese subjects, aged 18 to 25 were assessed using casts and photographs. Materials and Methods: Thirteen landmarks representing the most facial portions of the proximal contact areas on the maxillary and mandibular casts were digitised. Seventy-eight possible, Euclidean distances between the 13 landmarks were calculated using the Analysis ToolPak of Microsoft Excel®. The male-to-female ratios of the corresponding distances were computed and ratios were compared to evaluate the arch form for variation in the genders, among the Nepalese population. Statistical Analysis Used: Microsoft Excel Analysis ToolPak and SPSS 20.0 (IBM Chicago) were used to perform EDMA and an independent t-test to compare the significant differences between the two genders. Results: The maxillary arch's largest ratio (1.008179001) was discovered near the location of the right and left lateral incisors, indicating that the anterior region may have experienced the greatest change. The posterior-molar region is where the smallest ratio was discovered, suggesting less variation. At the intercanine region, female arches were wider than male ones; however, at the interpremolar and intermolar sections, they were similar in width. Females' maxillary arches were discovered to be bigger antero-posteriorly than those of males. The highest ratio (1.014336113) in the mandibular arch was discovered at the intermolar area, suggesting that males had a larger mandibular posterior arch morphology. At the intercanine area, the breadth of the arch form was greater in males and nearly the same in females at the interpremolar and intermolar regions. Female mandibular arch forms were also discovered to be longer than those of males from the anterior to the posterior. Conclusions: The male and female arches in the Nepalese population were inferred to be different in size and shape. With references to the landmarks demonstrating such a shift, the EDMA established objectively the presence of square arch forms in Nepali males and tapering arch forms in Nepalese females.

Innovations in assessment in health professions education during the COVID-19 pandemic: A scoping review.

BACKGROUND: After an initial period of uncertainty during the COVID-19 pandemic, medical universities responded to the pandemic by innovating their methods of teaching-learning and assessment. This scoping review aimed to identify innovations in assessment in medical, dental and nursing education at the undergraduate and postgraduate levels during the pandemic. METHODS: This review was conducted utilising Arksey and O'Malley's framework where three electronic databases-PubMed, Embase and Web of Science-were systematically searched in February 2022 for articles in English describing innovations in assessments published in or after January 2020. RESULTS: A total of 70 articles were included in the review. Among the primary research articles, 82.1% reported online assessment, 76.1% were related to medical speciality, 74.6% described assessment at the undergraduate level, 68.7% described summative assessment and 58.2% reported assessment of practical skills. All assessments of theoretical knowledge were done virtually with MCQ being the most used assessment tool and virtual OSCE being the most popular assessment tool to assess practical skills; however, it was acknowledged that the assessment of procedural skills was its limitation. Although the studies described the newer forms of assessments as feasible and acceptable, few studies reported the reliability and validity of the assessments. CONCLUSIONS: This scoping review identified several innovations in assessment during the COVID-19 pandemic with an overall shift towards virtual or hybrid forms of assessment. However, there was a dearth of evidence regarding the effectiveness of these assessment tools suggesting a need for more research before the tools can be implemented post-pandemic.

An Orthodontic Approach for the Correction of Transposition along with Multiple Impacted Teeth.

Impaction of teeth affects patients' esthetics, speech, and masticatory efficiency. In addition, the transposition of teeth makes a case difficult to manage. This case report describes a case of a 14-year-old boy with the impaction of the maxillary right central incisor and canine along with the transposition of the right canine and lateral incisor. The impacted teeth were surgically exposed and guided into the arch using orthodontic traction. Likewise, the transposition was corrected orthodontically by moving the teeth to their desired position without any detrimental effect on the adjacent teeth. The patient's esthetics and occlusion improved substantially after the orthodontic intervention.

Influence of Intraoral Scanners, Operators, and Data Processing on Dimensional Accuracy of Dental Casts for Unsupervised Clinical Machine Learning: An In Vitro Comparative Study.

Purpose: This study assessed the impact of intraoral scanner type, operator, and data augmentation on the dimensional accuracy of in vitro dental cast digital scans. It also evaluated the validation accuracy of an unsupervised machine-learning model trained with these scans. Methods: Twenty-two dental casts were scanned using two handheld intraoral scanners and one laboratory scanner, resulting in 110 3D cast scans across five independent groups. The scans underwent uniform augmentation and were validated using Hausdorff's distance (HD) and root mean squared error (RMSE), with the laboratory scanner as reference. A 3-factor analysis of variance examined interactions between scanners, operators, and augmentation methods. Scans were divided into training and validation sets and processed through a pretrained 3D visual transformer, and validation accuracy was assessed for each of the five groups. Results: No significant differences in HD and RMSE were found across handheld scanners and operators. However, significant changes in RMSE were observed between native and augmented scans with no specific interaction between scanner or operator. The 3D visual transformer achieved 96.2% validation accuracy for differentiating upper and lower scans in the augmented dataset. Native scans lacked volumetric depth, preventing their use for deep learning. Conclusion: Scanner, operator, and processing method did not significantly affect the dimensional accuracy of 3D scans for unsupervised deep learning. However, data augmentation was crucial for processing intraoral scans in deep learning algorithms, introducing structural differences in the 3D scans. Clinical Significance. The specific type of intraoral scanner or the operator has no substantial influence on the quality of the generated 3D scans, but controlled data augmentation of the native scans is necessary to obtain reliable results with unsupervised deep learning.

A Retrospective Study Comparing Nose, Lip, and Chin Morphology in Class I, Class II, and Class III Skeletal Relationships in Patients Visiting to the Department of Orthodontics, BPKIHS: A Cephalometric Study.

Background: With the changing paradigm from primarily hard tissue to soft tissue evaluation for orthodontic diagnosis and treatment planning, the priority has shifted to bring about improvement in the profile and smile characteristics of patients. Since not only the esthetics but also the stability of orthodontic treatment is largely determined by the soft tissue envelope, proper positioning of the soft tissue drape becomes paramount. Soft tissues of face, namely, nose, lips, and chin, are of paramount importance not only from an esthetic but also from functional and treatment stability points. Objective: To determine the morphological variation of lips, nose, and chin in different skeletal malocclusions. Materials and Methods: Lateral cephalograms of 237 patients visiting the department of orthodontics, BPKIHS, were taken, hand traced on matt acetate tracing paper of 0.002″ thickness with 0.3-mm 2B pencil. Samples were divided into 3 skeletal classes based on ANB angle. Measurements were made in relation to the nose, lips, and chin. Data were inserted in to SPSS and analyzed statistically using descriptive statistics, and mean and standard deviation was calculated for each variable. Multiple comparison between groups was done with post hoc Bonferroni test with mean difference significant at p < 0.05. Result: On intergroup comparison, a significant difference was found for upper lip thickness (ULT) between Class II and Class III, and lower lip length (LLL) between Class I and Class III, and between Class II and Class III. Significant difference for nasolabial angle (NLA) was found between Class II and Class III. Similarly, a significant difference for the vertical chin parameter (CTV) was found between Class I and Class III, and between Class II and Class III. Conclusion: Both upper and lower lip thicknesses were highest for Class III followed by Class I and Class II, respectively. Lip lengths too were found to be highest for Class III skeletal relation. Nasolabial angle was larger in Class II malocclusion when compared to Class I and Class III. Similarly, both nasal length and nasal height measurements were in the order of Class III > Class II > Class I. Both horizontal and vertical chin parameters were larger for Class III sagittal relation.

How common is ponticulus posticus on lateral cephalograms?

BACKGROUND: Ponticulus posticus is an anomaly of first cervical vertebra visible on lateral cephalogram and has some serious medical and surgical implications. Unfortunately, it is often overlooked or undetected by orthodontists. The general objective of this study is to sensitize orthodontists about this anomaly by depicting its prevalence among a group of Nepalese orthodontic patients. METHODS: Four hundred and fourteen digital lateral cephalograms of orthodontic patients were retrieved from the archives of the department. The lateral cephalograms were carefully assessed for the presence of ponticulus posticus in the posterior spine of atlas vertebra by two investigators independently and the findings were recorded. RESULTS: Ponticulus posticus was observed in 35.7% of the cases, of which 30.9% had partial ponticulus posticus and 4.8% had complete ponticulus posticus. Even though there was some female predilection, no statistically significant association was found between gender of the patient and presence of ponticulus posticus. CONCLUSION: Ponticulus posticus is a fairly common anomaly with more than one-third (35.7%) of a group of Nepalese orthodontic patients affected and is independent of gender. Since, this anomaly is associated with numerous medical conditions and has surgical implications, orthodontists should use lateral cephalogram as screening radiograph for this anomaly.

Translation and Validation of Modified Dental Anxiety Scale: The Nepali Version.

Introduction. For proper management of anxious dental patients it is imperative to assess their levels of dental anxiety before treatment. Modified Dental Anxiety Scale (MDAS) is the most commonly used questionnaire to assess dental anxiety. But a Nepali version of MDAS is still lacking. Hence, the objective of this study was to develop a reliable and valid Nepali version of MDAS. Materials and Methods. The English version of the MDAS was translated into Nepali following a forward and backward translation process. Following pretesting and cognitive interviewing a final version of Nepali questionnaire was obtained. One hundred and fifty patients attending Department of Orthodontics completed the Nepali version of MDAS questionnaire at their convenience. Also, patients were asked to rate their overall anxiety on a 100 mm visual analog scale (VAS). A test-retest of the questionnaire was performed with 30 patients after 2 weeks. Results. Cronbach's alpha value of the Nepali version of MDAS was 0.775. The Intraclass Correlation Coefficient between test and retest was 0.872. Spearman's correlation coefficient between the total MDAS score and VAS score was 0.838. Conclusion. The translated Nepali version of MDAS is a reliable and valid instrument to measure the dental anxiety of Nepali patients.

Orthodontic Treatment Need among Nepalese High School Students

Abstract Objective: To assess the need for orthodontic treatment among Nepalese high school students. Material and Methods: This is a quantitative, cross-sectional descriptive study. The sample comprises 938 children (537 males and 401 females) with an age group above 14 years. The subjects were selected voluntarily from seven different schools of Kathmandu valley using a multistage sampling technique. The Index of Orthodontic Treatment Need comprises two components: Dental Health Component (DHC) and Aesthetic Component (AC). Two trained and calibrated examiners performed the oral examination. Results: On analysis of the DHC component, it was found that 21% had no need, 18.1% had mild/little need, 24.3% had moderate/borderline need, 35.8% had severe need, and 0.7% had extreme treatment need. Similarly on analysis of AC component, it was found that 33% were AC-1, 30.8% were AC-2, 7.2% were AC-3, 8.2% were AC-4, 2.1% were AC-5, 3.6% were AC-6, 1.8% were AC-7, 7.4% were AC-8, 1.8% were AC-9, and 3.9% were AC-10. Conclusion: The Index of Orthodontic Treatment Need can be used as a tool for planning dental health resources and prioritizing the treatment need of different populations (AU).

Effect of Subject Rotation on Assessment of Esthetic Dental Ratios: A Simulation Study.

Objective. This study aimed to find out the change in esthetic ratios during rotation of patient's head using a simulation. Materials and Methods. A plaster study model was photographed placing its midline along the long axis of the camera. Then a series of photographs were taken by rotating the model each degree till 10° on both right and left sides. These photographs were digitally measured and the ratio of the maxillary anterior teeth at zero-degree rotation was compared with that at various degrees of rotation. Results. As the model was rotated to the right side till 10°, the ratio of the right lateral to central incisor gradually decreased while the ratio of the left lateral to central incisor gradually increased. However, the ratio of the canine to lateral incisor on both sides gradually increased. Similar results were obtained when the model was rotated to the left side. The ratio of the lateral to central incisor deviated from the acceptable range (±10%) when there was rotation of more than 7°, whereas the ratio of the canine to lateral incisor was within the acceptable range till 10° rotation on either side. Conclusions. Rotation of the model by more than 7° leads to a substantial change in the esthetic ratio.

Assessment of skeletal maturation with permanent mandibular second molar calcification stages among a group of Nepalese orthodontic patients.

BACKGROUND: Assessment of growth status of a patient is a key component in orthodontic diagnosis and treatment planning for growing patients with skeletal discrepancy. Skeletal maturation based on hand-wrist radiograph and cervical vertebral maturation (CVM) are commonly used methods of growth assessment. Studies have shown that stages of dental calcification can also be used to assess skeletal maturation status of an individual, whereas other studies have suggested that the relationship between dental calcification and skeletal maturation should be interpreted with caution owing to racial variation. OBJECTIVE: To evaluate the relationship between permanent mandibular second molar calcification stages and skeletal maturity assessed by CVM among a group of Nepalese orthodontic patients. MATERIALS AND METHODS: One hundred and sixty-eight digital radiographs (84 orthopantomograms and 84 lateral cephalograms) were obtained from the records of 84 patients who sought orthodontic treatment in Orthodontic and Dentofacial Orthopaedic Unit, Department of Dentistry, Institute of Medicine, Kathmandu. Two parameters were used in this study, namely, CVM stages from lateral cephalogram and Demirjian index (DI) stages from orthopantomogram. The evaluation of digital radiographs was carried out on a computer screen with a resolution of 1,280×800 pixels. The association between DI stages of permanent mandibular second molar and CVM stages was assessed. RESULTS: A statistically significant association was found between DI and CVM stages for both male and female subjects with Pearson's contingency coefficient value of 0.751 and 0.766 for male and female subjects, respectively. CONCLUSION: Skeletal maturation can be reliably assessed with dental calcification stages of permanent mandibular second molar for Nepalese orthodontic patients.